import math
x1,y1,x2,y2 = map(float,input().split(" "))
yoko = x2 - x1
tate = y2 - y1
print(math.sqrt(yoko**2+tate**2)) import math math x1,y1,x2,y2 = map(float,input().split(" ")) x1 map(float,input().split(" ")) map float input().split(" ") ().split () input split " " y1 x2 y2 yoko = x2 - x1 yoko x2 - x1 x2 x1 tate = y2 - y1 tate y2 - y1 y2 y1 print(math.sqrt(yoko**2+tate**2)) print math.sqrt(yoko**2+tate**2) math.sqrt math sqrt yoko**2+tate**2 yoko**2 yoko 2 tate**2 tate 2 y1,x2,y2 = map(float,input().split(" ")) map(float,input().split(" ")) y1 x2,y2 = map(float,input().split(" ")) map(float,input().split(" ")) x2 y2 = map(float,input().split(" ")) map(float,input().split(" ")) y2 yoko = x2 - x1 x2 - x1 yoko x1,y1,x2,y2 = map(float,input().split(" ")) map(float,input().split(" ")) x1 tate = y2 - y1 y2 - y1 tate
import math
x1,y1,x2,y2 = map(float,input().split(" "))
yoko = x2 - x1
tate = y2 - y1
print(math.sqrt(yoko**2+tate**2))